Halliburton Energy Services, Inc.

Baroid Technology, Inc.

David Philip McRobbie

John Lionel Weston

Peter A Leaney

A steerable bore hole drilling tool and method of drilling bore holes. The steerable bore hole drilling tool comprise means for mechanically decoupling the sensor unit from the tool body. The method comprises a step of mechanically decoupling the sensor unit form the tool body.

Closed loop control bore hole drilling system

One embodiment includes an apparatus comprising a steerable well bore drilling tool having a main tool body. The steerable well bore drilling tool includes an inertial measurement unit to output a measurement used to determine an azimuthal deviation and inclination of the steerable well bore drilling tool during a drilling operation.

Borehole drilling control system, method and apparatus

The invention relates particularly to sensing devices and techniques which may be used to provide measurement data to aid an inertial navigation system, or attitude and heading reference system, and so bound the growth of errors which increase with time in such systems when operating autonomously. In one aspect, the invention relates to a method of determining the path length along a borehole from a known reference point to a probe or tool which progresses through a drillpipe or tubular string, to provide data to aid an inertial navigation system. A sensing device 15 is used to detect joints 11 between sections of drillpipe or tubular string within the borehole and the path length is determined from the number of joints detected and a known length of each section of drillpipe or tubular string. In another aspect, a flow measuring device, such as an impeller, is used to measure the velocity of the probe or tool through the drillpipe or tubular string. In another aspect the invention relates to a method of determining the velocity of a probe or a tool moving through a drillpipe or tubular string to provide data to aid an inertial navigation system. Two sensing devices, which are spaced apart by a known distance on the probe or tool, are used to detect one or more positions within a drillpipe or tubular string, and the velocity of the probe or tool is determined from the elapsed time between each sensor detection of the or each position and the distance between the sensors.

Aided inertial navigation system

A rotating centralizer and a centralizing bearing assembly are provided in order to maintain a survey instrument assembly at a fixed angular orientation with respect to a core barrel supported by the bottomhole assembly of a rotating drill string and rotationally isolated therefrom. The centralizer comprises a sleeve having an inner bearing surface providing for rotation of the sleeve with respect to a support sub, and outer bearing surfaces located at the ends of four vanes allowing for rotation of the sleeve with respect to the surrounding drill string. The centralizing bearing assembly comprises a hanger sub, an outer sleeve which is a force fit within a hang-off sub of the drill string and an annular roller bearing unit surrounding the hanger sub and engaging the inner surface of the outer sleeve. The roller bearing unit comprises a plurality of tapered roller bearings having inclined axes of rotation. Such an arrangement is advantageous as it provides the required rotational isolation without the survey instrument assembly being subjected to substantial axial movement or torsion in operation.

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Aberdeen, United Kingdom

David Philip McRobbie